jeff.proto-_-

Go with the dual, both will be pretty much the same in real-world performance. And the dual is 15% chealper

ear plugs

its always a good idea to have some headroom. lets say your running 435 watts worth of components through a 450 watt PSU. Adding more to the load in the future can potentially run you into your limit and can also limit if you want or can even push your parts further like overclocking. Personally id go with at least 100W over what your pc says it can pull, but as @jeff.proto-_- said, if its a good PSU, it should be fine up to its rated wattage.

It might not, 4 slots is not enough for 2 GPUs, as the 16x/8x slots are normally 1 slot apart
 
edit: oops didnt read

The 8600k would be your best option then. Just wait until the price of coffee lake motherboards drops down next year

Ebay is fine for buying CPUs. It's not a bad idea at all.

Games are mostly single-threaded and the 4690K is fine for that, the i5 and the i7 both use the same 22nm process and share the same per-core performance

Just upgrading the GPU to a 1070 Ti or a 1080/Ti should do the trick. The 4690K is still capable of more than 60 FPS

Wait until next year to upgrade to coffee lake, there are currently only Z370 motherboards that are really expensive

Wait until next year to upgrade to coffee lake, there are currently only Z370 motherboards that are really expensive

Wait until next year to upgrade to coffee lake, there are currently only Z370 motherboards that are really expensive

Wait until next year to upgrade to coffee lake, there are currently only Z370 motherboards that are really expensive

You'll probably kill your components, don't try it

The 980ti SLI would easily outperform Vega 64, get the 980ti's

Have you tried changing the GPUs PCI-E slot to see if it's the motherboard?

The stop code is important, without it we can't help you. Write it down when you get your next BSOD

If it says MEMORY MANAGEMENT, you may need to replace your RAM, If it says SYSTEM_THREAD_NOT_HANDLED or something like that then you'll need to update your drivers

To OC your gpu, get ASUS GPU Tweak or MSI Afterburner. You will also need AIDA 64 to stress test the OC to make sure that it's stable. DO NOT BIOS FLASH, YOU MAY BRICK YOUR CARD! OC in roughly 50MHz increments until you hit the clocks you are comfortable with.

Glad I could help

This may be a bit expensive, but this is a thin and light i7 laptop. https://www.amazon.co.uk/ASUS-UX430UA-GV232T-14-inch-ZenBook-Screen/dp/B0742FK5C1/ref=sr_1_46?s=computers&ie=UTF8&qid=1508163835&sr=1-46&keywords=laptop+13+inch+screen

I didn't realise the prices, you should get the PC.

Okay, here's a laptop that may be good for your needs: https://www.amazon.co.uk/ASUS-X542UA-GO254T-VivoBook-15-6-inch-Notebook/dp/B073Q44QR8/ref=sr_1_10?s=computers&ie=UTF8&qid=1508163524&sr=1-10&keywords=laptop

Are you buying the Xeon brand new? If you are, you'd be better off going with Intel's enthusiast platform (X299 and X99). It would also be a better value than an X79 Xeon system.